Using a data sample of $921.9{\mathrm{fb}}^{-1}$ collected with the Belle detector, we study the process of $e^{+}{e}^{-}\to D_s^{+}{D}_{s1}(2536{)}^{-}+\mathrm{c}.\mathrm{c}.$ via initial-state radiation. We report the first observation of a vector charmoniumlike state decaying to $D_s^{+}{D}_{s1}(2536{)}^{-}+\mathrm{c}.\mathrm{c}.$ with a significance of $5.9\sigma$, including systematic uncertainties. The measured mass and width are $({4625.9}_{-6.0}^{+6.2}(\text{stat})\pm 0.4(\text{syst}))\mathrm{MeV}/c^2$ and $({49.8}_{-11.5}^{+13.9}(\text{stat})\pm 4.0(\text{syst}))\mathrm{MeV}$, respectively. The product of the $e^{+}{e}^{-}\to D_s^{+}{D}_{s1}(2536{)}^{-}+\mathrm{c}.\mathrm{c}.$ cross section and the branching fraction of $D_{s1}(2536{)}^{-}\to {\overline{D}}^{*0}{K}^{-}$ is measured from the $D_s{\overline{D}}_{s1}(2536)$ threshold to 5.59 GeV.

• Received 2 November 2019
• Revised 26 November 2019

DOI:https://doi.org/10.1103/PhysRevD.100.111103

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society